|A Grumman G-111 Albatross amphibious flying boat landing|
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A seaplane is a powered fixed-wing aircraft capable of taking off and landing (alighting) on water. Seaplanes that can also take off and land on airfields are a subclass called amphibian aircraft. Seaplanes and amphibians are usually divided into two categories based on their technological characteristics: floatplanes and flying boats; the latter are generally far larger and can carry far more. These aircraft were sometimes called hydroplanes, but currently this term applies instead to a motorboats that float on hydrofoils.
The word "seaplane" is used to describe two types of air/water vehicles: the floatplane and the flying boat.
- A floatplane has slender pontoons, or floats, mounted under the fuselage. Two floats are common, but other configurations are possible. Only the floats of a floatplane normally come into contact with water. The fuselage remains above water. Some small land aircraft can be modified to become float planes, and in general floatplanes are small aircraft. Floatplanes are limited by their inability to handle wave heights typically greater than 12 inches (0.31 m). These floats add to the empty weight of the airplane, and to the drag coefficient, resulting in reduced payload capacity, slower rate-of-climb, and slower cruise speed.
- In a flying boat, the main source of buoyancy is the fuselage, which acts like a ship's hull in the water because the fuselage's underside has been hydrodynamically shaped to allow water to flow around it. Most flying boats have small floats mounted on their wings to keep them stable. Not all small seaplanes have been floatplanes, but most large seaplanes have been flying boats, with their great weight supported by their hulls.
The term "seaplane" is used by some instead of "floatplane". This is the standard British usage. This article treats both flying boats and floatplanes as types of seaplane, in the US fashion.
An amphibious aircraft can take off and land both on conventional runways and water. A true seaplane can only take off and land on water. There are amphibious flying boats and amphibious floatplanes, as well as some hybrid designs, e.g., floatplanes with retractable floats. Modern production seaplanes are typically light aircraft, amphibious, and of a floatplane design.
The first manned and controlled (though unpowered) hydroplane flight took place in June 1905 and was established by French aircraft designer, builder and pilot Gabriel Voisin, on the river Seine; it was a towed flight, at 15 to 20 m altitude (50 to 66 ft), and 600 meters (2000 ft) long. The aircraft was a biplane with an aft tail and a front elevator, supported at rest by 2 planing floats (catamaran).
The first autonomous flight by a hydroplane was made by the French engineer Henri Fabre on March 28, 1910. Also a floatplane, its name was Le Canard ('the duck'), and took off from the water to fly 1,650 feet on its first flight. These experiments were closely followed by Gabriel and Charles Voisin, who purchased several of the Fabre floats and fitted them to their Canard Voisin which flew in October 1910. In March 1912, it was used in military exercises from the first seaplane carrier, La Foudre.
In the United States, early development was carried out at Hammondsport, New York by Glenn Curtiss who had beaten Alexander Graham Bell and others in the Aerial Experiment Association. The first American seaplane flight occurred on January 26, 1911 by Curtiss in his "hydroaeroplane" from the waters of San Diego Bay., with much of the later development of Curtiss seaplanes occurring from the surface of Keuka Lake in New York State, on whose southern end Hammondsport is located.
In June 1911, in co-operation with Edouard Perrot (Edouard Perrot & Cie), Emile Taddéoli started to design the seaplane "La Mouette" in Switzerland, and before, began tests with a Dufaux 4 biplane equipped with swimmers. On March 26, 1912, a first takeoff was not successful, and "La Mouette" was destroyed. In summer 1912, René Grandjean replaced the skis of his aircraft by floats designed and engineered by himself, resulting in the first takeoff of a Swiss hydroplane (seaplane) on August 4, 1912.
Origins of Maritime Aviation in Britain - It is widely recognized that Orville Wright made the world’s first successful powered flight on 17 December 1903, though the first powered flight in Britain was not made until 1908. At an aviation meeting in Blackpool in 1909, two Westmorland-based men, Captain Edward Wakefield and Oscar Gnosspelius, discussed the feasibility of flight from water, as it was soon recognized that operating aircraft from water had the advantage of rendering accidents more survivable. They decided to make use of Windermere, England’s largest lake. Gnosspelius designed his own aircraft and persuaded Windermere boat-builder Arthur Borwick to build it for him. His first attempts to fly attracted large crowds, though the aircraft failed to take off and required a re-design of the floats incorporating features of Borwick’s successful speed-boat hulls. Meanwhile, Wakefield built a hangar on his land at Hill of Oaks on Windermere and, following the world’s first successful flight from water on 28 March 1910 ("Le Canard," designed and flown by Henri Fabre from Lac Berre near Marseille), Wakefield ordered a floatplane of similar design, subsequently named “Waterbird.” By November 1911, both Gnosspelier and Wakefield had aircraft capable of flight from water and awaited suitable weather conditions. At the same time, Commander Oliver Schwann, Royal Navy, was conducting similar experiments in Cavendish Dock, Barrow in Furness and, on 18 November, Schwann took off from the dock but soon crashed back onto the water. A week later, on 25 November 1911, Gnosspelier taxied into Windermere’s Bowness Bay and took off, though this flight was short-lived – a wing clipped the water, the aircraft flipped onto its back and crashed into the lake. Grosspelier was able to climb out unhurt and was rescued. Meanwhile, 6 km. to the south at Hill of Oaks, Wakefield’s pilot, Stanley Adams, was unaware of the events in Bowness Bay. After an unsuccessful attempt to lift off from the lake, he took advantage of a light northerly wind and flew at a height of 50 feet to Ferry Nab, where he made a wide turn and returned to Hill of Oaks for a perfect landing on the lake’s surface, the first successful British flight from water.
The Lakes Flying Company Limited is, as of 2011, building a flying replica of “Waterbird,” which is expected to fly from Windermere during the British Floatplane Centenary year. (ABL, Sep. 2011).
The first in history combat missions of a seaplane was probably those of a Greek "Astra Hydravion" between December 1912 and January 1913, during the Balkan Wars. In one of them, on January 24, 1913, the seaplane with two Greek pilots flew at 1200 meters over the Dardanelles from the European to the Asian coast, did a reconnaissance of the Turkish fleet, dropped 4 bombs and after 2 hours flight landed at sea near the island of Imbros. The plane was targeted by canons and rifles unsuccessfully.
Englishman John Cyril Porte joined with Curtiss to design a transatlantic flying boat, and developed a more practical hull for Curtiss' airframe and engines with the distinctive 'step' which enabled the hull and floats to cleanly break free of the water's surface at take-off. In the UK the Curtiss flying boat was developed into the Felixstowe series of flying boats, which were used in the First World War to patrol for German submarines. Curtiss N-9 seaplanes were used during World War I as primary trainers, and over 2,500 Navy pilots learned to fly in them. A handful of N-9s were used in the Hewitt-Sperry Automatic Airplane project to develop an "aerial torpedo" or flying bomb, an early RPV.
Because of the lack of runways and the perceived safety factor over water, many commercial airlines including Imperial Airways (fore-runner of BOAC), and Pan-American World Airways used large flying boats to provide service for long distance service across the Atlantic, Pacific and Indian Oceans. Aircraft specially built for these routes included some of the largest aircraft built between the wars.
- Aeromarine 75
- Boeing Clipper
- Consolidated Commodore
- Dornier Wal
- HU-16 Albatross
- Latécoère 631
- Martin China Clipper
- Sikorsky VS-44
- Short Kent
- Short Empire
Smaller carriers found them useful as well for operating into areas without prepared runways. Popular with bush operators, sportsmen and explorers, a huge variety of designs were built. Examples include:
- Sikorsky S-38
- Sikorsky S-39
- Grumman Goose
- Grumman Mallard
- Grumman Albatross
- Douglas Dolphin
- Dornier Delphin
- Supermarine Sea Eagle
- Vickers Viking
- Canadian Vickers Vedette
- Beriev MBR-2
Typical for the above types, the Grumman Goose came about in 1936, when a group of wealthy industrialists, including Henry Morgan, Marshall Field and E.R. Harriman, wanted an easier way to commute from their homes on Long Island, New York, to the financial district of Wall Street. They commissioned Roy Grumman to build ten airplanes that could take off from their private air strips and land on the water near the financial district. Grumman re-engineered their amphibians after the war and built a commercial version of their durable amphibians, called the Grumman Mallard.
During World War II, most navies used seaplanes for reconnaissance, search and rescue, and anti-submarine warfare. Possibly the most commonly known was the Consolidated PBY Catalina which was flown by the United States, United Kingdom, Russia, and Canada, among many others. Similar aircraft were used by Japan, Germany, Italy.
The US Navy utilized a fleet of seaplanes for reconnaissance, rescue and had many fitted with machine guns and bombs. Most battleships carried one or two (some cases as many as four) catapult-launched seaplanes to spot targets over the horizon for the big guns, or to fight off enemy reconnaissance planes.
- Aichi E13A
- Arado 196
- Blohm & Voss BV 222 Wiking
- CANT Z.501
- Dornier Do 18
- Dornier Do 24
- Kawanishi H8K "Emily"
- Mitsubishi F1M
- Consolidated Catalina
- Consolidated Coronado
- Martin Mariner
- Short Sunderland
- Supermarine Sea Otter
- Supermarine Stranraer
- Supermarine Walrus
The largest aircraft built during the World War II years by any of the Axis powers would be the single flyable prototype of the Bv 238 six-engined maritime patrol flying boat, possessing a maximum takeoff weight of 100 metric tons in 1945.
In the post war period the availability of large paved runways and the greatly expanded performance of land-based planes meant that both commercial and military use of seaplanes was much reduced. Anti-Submarine Warfare was just as easily carried out with land based aircraft, which often had better performance, and Search and Rescue could more easily be carried out with helicopters, which had the advantages of being operated from smaller ships, and in higher sea states. The compromises that came from being able to float and rise again from the water caused excessive drag and added considerably to the weight of the aircraft. In commercial service this translated into increased costs, and for a military aircraft, into reduced warloads, speeds and ranges.
Only in specialized roles were they able to remain competitive, such as waterbombing, where their ability to quickly reload was a huge asset. A number of surplus WW2 seaplanes including the PBY and Martin Mars were initially used in this role but their advancing age has required a new specially designed aircraft in the form of the Canadair CL-215, which operates alongside second-hand land-based bombers and transports.
The only amphibian aircraft produced for post war commercial usage was the Grumman Mallard which was designed as a true airliner, with modern technology and longer ranges, greater passenger and cargo loads. The Mallard saw production from 1946-1951. Only 59 were delivered, used mostly by corporations and some regional commuter carriers.
The British and the US experimented with jet-powered seaplane fighters such as the Saunders-Roe SR.A/1 and the F2Y Sea Dart but despite some successes (the US fighter became the only supersonic seaplane to date), these did not enter service. An attempt was made in the early to mid-1950s to develop a large jet-powered flying boat (the Martin P6M SeaMaster) for the U.S. Navy. Although several prototypes were built and tested, the project, like those of the fighters, was eventually terminated.
The U.S. Navy, however, continued to operate seaplanes and seaplane tenders, especially in the Far East, until the mid-1970s. Both Japan and Russia continued operating military seaplanes even later, including the ShinMaywa US-1 and Beriev Be-12, primarily for Anti-Submarine Warfare, where they can take advantage of their range and speed over helicopters, while still able to land on water.
Seaplanes are still being used for firefighting and sightseeing, but have been replaced in nearly all military roles by helicopters.
Uses and operation 
Numerous modern civilian aircraft have a floatplane variant, usually for light duty transportation to lakes and other remote areas. Most of these are offered as third-party modifications under a supplemental type certificate (STC), although there are several aircraft manufacturers that build floatplanes from scratch, and a few that continue to build flying boats. Many older flying boats remain in service for fire-fighting duty, and Chalk's Ocean Airways operated a fleet of Grumman Mallards in passenger service until service was suspended after a crash on December 19, 2005, which was linked to maintenance, not to design of the aircraft. Purely water-based seaplanes have largely been supplanted by amphibious aircraft.
Seaplanes can only take off and land on water with little or no wave action and, like other aircraft, have trouble in extreme weather. The size of waves a given design can withstand depends on, among other factors, the aircraft's size, hull or float design, and its weight, all making for a much more unstable aircraft, limiting actual operational days. Flying boats can typically handle rougher water and are generally more stable than floatplanes while on the water.
Rescue organizations, such as coast guards, are among the largest modern operators of seaplanes due to their efficiency and their ability to both spot and rescue survivors. Land-based aircraft cannot rescue survivors, and many helicopters are limited in their capacity to carry survivors and in their fuel efficiency compared to fixed-wing aircraft. (Helicopters may also be fitted with floats to facilitate their usage on water, though they are not referred to as seaplanes.) These are even more limited in range.
Water aircraft are also often used in remote areas such as the Alaskan and Canadian wilderness, especially in areas with a large number of lakes convenient for takeoff and landing. They may operate on a charter basis, provide scheduled service, or be operated by residents of the area for private, personal use. Seaplanes are used in Greece to connect the many islands to the mainland. In the Western Hemisphere, there are numerous seaplane operators in the Caribbean Sea that offer service within or between island groups.
See also 
- Amphibious aircraft
- Flying boat
- List of flying boats and seaplanes
- Auxiliary cruiser
- Seaplane tender
- IAR 111
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- Gunston, "The Cambridge Aerospace Dictionary", 2009.
- de Saint-Exupery, A. (1940). "Wind, Sand and Stars" p33, Harcourt, Brace & World, Inc.
- The Oxford English Dictionary defines "seaplane" as An aeroplane designed to be able to operate from water; specifically, one with floats, in contrast to a flying boat.
- Dictionary definition, "Flying boat"
- Dictionary definition "Floatplane"
- Dictionary definition, "Seaplane"
- Anonymous (2009) The establishment of the Navy Airforce, Fox2 Magazine (in Greek language)
- Stephane Nicolaou (1996) Flying Boats & Seaplanes: A history from 1905, Bay Books View Ltd, Devon, 1998, p. 49